1. Field of the Invention
The present invention relates to an electric charging system and an electric charger, and, in particular, to a technology for preventing the erroneous determination of the state of charge of an electric storage device charged with an electric charger.
2. Description of the Related Art
In recent years, electric vehicles that are equipped with an electric motor for propulsion have been under development. When an electric storage device such as a battery that is installed at the electric vehicle is charged, a charging cable extending from an electric charger is connected to a charging port of the electric vehicle (see, for example, Japanese Unexamined Patent Application Publication No. 2009-83670). Furthermore, in the field of hybrid electric vehicles that are equipped with an engine and an electric motor for propulsion, a hybrid electric vehicle of the so-called plug-in system, in which an electric storage device can be charged with an electric charger, is under development.
However, since the charging cable has an electric resistance and an impedance, a voltage drop occurs in the charging cable during charging. Thus, since a difference occurs between a supplied voltage the electric charger side and a received voltage at the electric vehicle, charging of the electric storage device is difficult to determine with high accuracy on the basis of the supplied voltage at the electric charger side. As a result, the state of charge of the electric storage device cannot be accurately confirmed with the electric charger, and appropriate charging control is difficult to perform with the electric charger.